EA036244B1 - Anti-icing additive composition for bituminous conglomerates - Google Patents

Abstract

An anti-icing composition suitable for incorporation in bituminous conglomerates for road paving, comprising an alkali metal chloride, an alkaline-earth metal carbonate, an alkali or alkaline-earth metal formate, a polysiloxane and optionally an alkaline-earth metal chloride, in which the polysiloxane is contained in an amount between 0.5 and 2.0 wt.% of the total weight of the composition; it is also described a bituminous conglomerate adapted to provide an anti-icing road paving, comprising aggregates, bitumen, filler and from 2 to 6 wt.% of such anti-icing composition of the weight of the aggregates.

Description

Technology area

The present invention relates to the field of obtaining bituminous conglomerates for road surfaces.

In particular, the invention relates to an additive composition for bituminous conglomerates that prevents, reduces or slows down the formation of ice on the road surface.

State of the art

It is well known that in winter the adhesion of the tire to the road surface is significantly reduced due to icing of the specified surface, causing the risk of slipping, loss of control and reduced braking properties of vehicles.

It is also known that in order to reduce the above risks, the road surface is usually pre-treated with salts, usually sodium chloride, which lower the freezing point of water in order to prevent ice formation and prevent snow from adhering to the road surface.

It is obvious, however, that these salts should be applied immediately before the beginning of a snowfall or a sharp drop in temperature in conditions of high air humidity, but this does not always happen or not along the entire length of the road.

In some cases, electrical resistors are placed in road surfaces, but this requires significant production and maintenance costs, and also reduces the stability of the road surface.

It is also proposed in regions with a high risk of ice formation to make pavement from special bituminous conglomerates containing additives to prevent or reduce ice formation.

For example, patent application EP 0332803 relates to an anti-icing coating obtained by including in a bituminous conglomerate from 3 to 5% of a granular mixture containing an alkali chloride, a thermoplastic material and an additive such as talc, cement or polyurethane powder.

Another example is given in patent application EP 0506984, which describes an anti-icing composition containing 5-95% of an alkali metal and / or alkaline earth metal chloride and 515% of an alkali metal alkenesiliconate, which is incorporated into a bitumen conglomerate or applied directly to the road surface.

Patent application WO 2007/096690 describes an anti-icing composition that is introduced into a bituminous conglomerate containing an alkali and / or alkaline earth metal salt with a molecular weight of less than 200 Da, for example sodium or calcium formate or acetate, and at least one surfactant a substance, preferably an alkylamide-polyamine and optionally also a siloxane.

The applicant of the present application has for several years been producing and marketing a de-icing composition suitable for inclusion in bituminous conglomerates called Winterpav, which contains sodium chloride, calcium chloride, sodium formate and calcium carbonate. The composition has proven to be very effective in preventing or at least substantially reducing ice formation on the surface of the pavement containing it, and the anti-icing effect is maintained for many months.

In addition, it was shown that the presence of the specified composition in the conglomerate for the road surface in amounts of up to 5 wt.% Based on the weight of the conglomerate does not lead to a significant change in the physical and mechanical properties of the road surface obtained using the composition.

However, the specified de-icing composition has some disadvantages associated with the processing and storage of the composition. Since the composition is a composition of solid compounds in the form of a powder with different particle sizes, in which very small particles are also present, there is a risk of inhalation of these particles by operators during use. In addition, some components, in particular calcium chloride and sodium chloride, are highly hygroscopic, which can lead to caking during storage.

In view of the prior art described above and, above all, the disadvantages indicated with reference to the Winterpav product, it was an object of the present invention to provide an anti-icing composition suitable for incorporation into bituminous paving conglomerates, which has an efficacy similar to the above product. and at the same time is devoid of the indicated disadvantages.

The essence of the invention

This problem is achieved by providing an anti-icing composition suitable for inclusion in bituminous conglomerates for a pavement, which contains an alkali metal chloride, an alkaline earth metal carbonate, an alkali or alkaline earth metal formate, a polysiloxane and, optionally, an alkaline earth metal chloride, when the content of polysiloxanes is 0.5 to 2.0% by weight, based on the total weight of the composition.

Preferably the composition comprises an alkali metal chloride and an alkaline earth metal chloride, preferably the alkali metal chloride is sodium chloride and the alkali metal chloride is calcium chloride.

Preferably, the alkaline earth metal carbonate is calcium carbonate.

Preferably the composition contains an alkali metal formate, usually sodium formate.

The polysiloxane is preferably a polydimethylsiloxane or dimethicone, the viscosity of which is preferably 300 to 400 mm ² / s, typically 325 to 375 mm / s at 25 ° C.

A particularly preferred de-icing composition consists of the following components, the contents of which are indicated in percent by weight based on the total weight of the composition:

sodium chloride - 60-84, sodium formate - 5-15, calcium chloride - 5-15, calcium carbonate - 2-8, polysiloxane - 0.5-2.0.

All percentages stated in the text of this application should be understood as weight percentages, unless otherwise indicated.

By means of the deicing composition according to the invention, a bituminous composition can be prepared for use as a component of a bituminous conglomerate.

The bitumen composition obtained from the de-icing composition according to the present invention generally contains from 20 to 70% of the specified de-icing composition and from 30 to 80% of bitumen.

Preferably, the bitumen composition contains from 30 to 60% of the specified anti-icing composition and from 40 to 70% of bitumen.

The bituminous composition can, in turn, be used to obtain a bituminous conglomerate for anti-icing road surfaces. The specified bitumen conglomerate contains aggregates, including, for example, inert, inorganic materials such as crushed stone, granular and crushed slag, artificial aggregates obtained, for example, by high-temperature melting of certain minerals or rocks (for example, bauxite or certain clays), fillers and, if necessary, polymeric materials in granular form, in addition to the aforementioned bituminous composition, which are usually contained in amounts of from 3 to 10 wt.%, based on the weight of the aggregates.

Alternatively, the deicing composition according to the invention can be added directly to the bitumen conglomerate containing aggregates, fillers and bitumen, and mixed with it in such an amount that the finished bitumen conglomerate contains from 2 to 6%, preferably from 3 to 5% by weight of said composition based on the weight of the aggregates.

The present invention also relates to a bituminous conglomerate capable of providing an anti-icing pavement comprising aggregates, fillers and bitumen and 2 to 6%, preferably 3 to 5% by weight, based on the aggregate weight of the above anti-icing composition, and bituminous conglomerate, made with the possibility of providing an anti-icing road surface containing aggregates, fillers and from 3 to 10 wt.% based on the mass of aggregates of the above anti-icing bitumen composition.

Another aspect of the present invention relates to a method for producing a bitumen conglomerate adapted to provide an anti-icing pavement, comprising the step of adding, with stirring and at a temperature of 130 to 200 ° C, the above-described bitumen and an anti-icing composition to a mixture of aggregates and fillers.

Another aspect of the present invention relates to a method for producing a bituminous conglomerate adapted to provide an anti-icing pavement, comprising the step of adding, with stirring and at a temperature of 130 ° C to 200 ° C, a mixture of aggregates and fillers of the above-described anti-icing bitumen composition.

Finally, the present invention relates to a process for the preparation of an anti-icing composition as described above, which comprises the steps of mixing an alkali metal chloride, an alkaline earth metal carbonate, an alkali or alkaline earth metal formate and, optionally, an alkaline earth chloride to form a mixture in the form of a homogeneous powder and adding the polysiloxane dispersed in finely divided form to said mixture as a homogeneous powder.

Thus, the polysiloxane evenly covers the powder granules, including the finest ones, and prevents them from spreading in the air during the loading and transportation of the deicing composition according to the invention, which prevents the risk of inhalation by people involved in these works.

Preferably, the step of adding the polysiloxane is carried out by spraying the polysiloxane with a spray device onto the mixture in the form of a homogeneous powder, mixed in a mixer, preferably in a screw mixer.

When added to bituminous paving conglomerates, an anti-icing composition according to the present invention provides a pavement capable of preventing or at least significantly reducing the formation of ice on the surface without significantly altering the physical and mechanical properties of a road surface obtained from the same bituminous conglomerate without the addition of an anti-icing composition.

The de-icing effect that the de-icing composition included in the bituminous conglomerate imparts to the road surface remains substantially unchanged for at least two months, usually for about 12 months, then gradually decreases, but provides good de-icing protection for more 24 months.

In addition, the composition according to the present invention is easy and safe to handle as it does not contain fine powders that can be inhaled by workers.

In addition, the composition of the present invention can be stored for extended periods of time, even for many months, without caking, and retains flow properties unchanged over time, which are important when the composition is added to a bituminous conglomerate to ensure accurate and reproducible dosing.

The characteristics and advantages of the present invention are additionally demonstrated by some variants of its implementation, which are further given by way of illustration and are not limiting, with reference to the accompanying drawings.

Brief Description of Drawings

FIG. 1 is a photograph of a fragment of a road surface obtained in the laboratory from a bituminous conglomerate A according to example 6, containing an anti-icing composition according to example 1.

FIG. 2 is a photograph of a fragment of a road surface obtained in the laboratory from the bitumen conglomerate B according to example 6, without the de-icing composition according to the present invention.

Detailed description of the invention

The following are some examples of the obtained de-icing compositions in accordance with the present invention, which have been tested with positive results in terms of preventing the formation of ice.

Example 1. Sodium chloride 70% Calcium chloride 13% Sodium formate eleven% Calcium carbonate 5% Dimethicone, viscosity 350mm ² / s at 25 ° С one% Example 2. Sodium chloride 80% Sodium formate 12% Calcium carbonate 6% Dimethicone, viscosity 300mm ² / s at 25 ^О С 2% Example 3. Sodium chloride 60% Calcium chloride 15% Sodium formate 15% Calcium carbonate 8% Dimethicone, viscosity 400mm ² / s at 25 ° С 2% Example 4. Sodium chloride 84% Calcium chloride 5% Sodium formate 5% Calcium carbonate 5.5% Dimethicone, viscosity 350mm ² / s at 25 ° С 0.5%

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The compositions in examples 1-4 were prepared by mixing the various salts indicated, with the exception of calcium carbonate, as coarse powders in a screw mixer and evenly spraying dimethicone thereon with a spray gun while mixing the salts. After the addition of dimethicone, powdered calcium carbonate was added with stirring and stirring was continued until a homogeneous mixture was obtained.

Example 5 (comparative).

Sodium chloride 71%

Calcium chloride 13%

Sodium formate 11%

Calcium carbonate 5%

The composition was prepared by metering the ingredients in the form of a coarse powder in a screw mixer with stirring, stirring was continued until a homogeneous mixture was obtained.

Example 6.

Using the composition according to example 1 in the laboratory received three blanks of bituminous conglomerate containing components in the proportions indicated in table. 1, the diameter of the preform was 100 mm, the thickness was about 25 mm. Also prepared three blanks from bitumen conglomerate with the same composition, but not containing the above composition.

Table 1

Bituminous conglomerate A containing the composition according to Example 1 Bituminous conglomerate B, not containing composition according Example 1 Materials Bulk parts Bulk parts Inert components 6/12 twenty twenty Inert components 3/8 fifty fifty Sand 0-4 25 25 Filler (CaCOj) 5 5 Bitumen 50/70 5.5 5.5 Composition according to Example 1 4 0 Total 109.5 105.5

Bituminous conglomerate was obtained in the laboratory by heating aggregates (inert materials, sand) and filler to a temperature of 180 ° C in a 5-liter planetary mixer and adding to them with stirring bitumen heated to 150 ° C, and in the case of bitumen conglomerate A, also a composition according to Example 1, in both cases at room temperature, after which stirring was continued for 5 minutes.

Then, the bitumen conglomerate was removed from the planetary mixer, measured in amounts of about 300 g into a porcelain container and placed in a rotary press (30 cycles) maintained at 150 ° C under a pressure of about 600 kPa to obtain corresponding blanks with a diameter of 100 mm, a thickness of about 30 mm and weighing about 100 g.

Three preforms of conglomerate A and three preforms of conglomerate B were then placed on the corresponding non-metallic discs and placed in a refrigerator at a temperature of 5 ° C for at least 2 hours to thermally normalize the samples. Then, water was sprayed onto the surface of the blanks at a temperature of 4 ° C (to simulate rain and snow), 6 sprays (about 8-9 ml) and stored in a refrigerator at -5 ° C for another 12 hours, after which a visual inspection of the blanks was carried out to determine the possible the presence of frost or ice on their surface.

If there was no frost or ice, the workpiece was brought back to room temperature, excess water was removed, the disc was cleaned, the workpiece was immersed three times in water in containers and normalization was repeated in a refrigerator at -5 ° C, water spraying at 4 ° C and storage in refrigerator at -5 ° C for 12 hours, checking afterwards for possible formation of ice or frost.

FIG. 1 and 2 show corresponding photographs of a bitumen conglomerate preform A and a bitumen conglomerate preform B. In particular, FIG. 2 shows a billet of bitumen conglomerate B after only one cycle of normalization, water spraying and storage at -5 ° C for 12 hours, and FIG. 1 shows a preform of conglomerate A after the 5 described cycles, immersed in water as described above between each cycle. Obviously, there is no ice on blank A, whereas

- 4 036244 on the workpiece B is clearly visible layer of ice formed at the end of the first stage of the above method.

Thus, the presence of the deicing composition according to Example 1 of the present invention in the bituminous conglomerate A completely prevents the formation of ice, and the conglomerate B, similar to the conglomerate A, except for the absence of the composition according to example 1, did not have any anti-icing effect.

Example 7.

The absorption of moisture from the atmosphere by the composition according to example 1 was determined and compared with the composition according to example 5, which did not contain dimethicone.

Verification was carried out by depositing a carefully measured amount of each of the above compositions on four corresponding glass Petri plates and exposing the plates to atmospheric air at a temperature of about 20 ° C for the periods indicated in table. 2. At the end of each period, the amount of absorbed moisture (moisture content in%) was determined using a thermal balance at 120 ° C for 20 minutes.

table 2

Time Example 1 (humidity,%) Example 5 (moisture,%) 1 day 1.02 2,3 30 days 1.7 4.6 60 days 2.0 9.5 90 days 1.8 9.3

From the results presented in table. 2, it is evident that the presence of the polysiloxane in the composition according to the present invention provides the composition with a high degree of protection against atmospheric humidity and as a result provides the aforementioned advantage of preventing caking and reducing flow properties.

Example 8.

The compositions in accordance with the present invention were added to the bituminous conglomerate and the change in the physical and mechanical properties of the wear layer made of said conglomerate was monitored.

For testing, samples of bituminous conglomerate were made in accordance with the SMA curve, as shown in table. 3.

Table 3

Bituminous conglomerate SMA1 containing the composition according to Example 1 Bituminous conglomerate SMA2, not containing the composition according to Example 1 Materials Bulk parts Bulk parts Inert materials 6/12 ten ten Inert materials 3/8 60 60 Sand 0-4 twenty twenty Filler (CaCOj) ten ten Plastomers and microfibers 0.6 oh, 6 Bitumen 50/70 6.5 6.5 Composition according to Example 1 4 0 Total 111.1 107.1

Samples were prepared by depositing about 1.2 kg of bitumen conglomerate in a cylindrical container, which was maintained at 150 ° C for at least 2 hours, and pressing it in a rotary press to form a corresponding cylindrical sample 100 mm in diameter and about 65 mm in height. For each sample, physical and mechanical measurements were performed, indicated in table. 4.

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Table 4

Conglomerate SMA1 Conglomerate SMA2 Specifications Residual voids (%) after 10 cycles 12.5 10.5 9-13 Residual voids (%) after 120 cycles 4.6 3.8 2-5 Residual voids (%) after 200 cycles 3.5 1.1 > 1 GMM ¹ after 200 cycles (maximum specific gravity) (kg / m ⁵ ) 2449 2384 GMB ² after 200 cycles (bulk density) (kg / ^m3) 2365 2358 ITS ³ after 200 cycles 20 ° C (N / mm ² ) 1.30 1.33 1.0-1.80 CTI ⁴ after 200 cycles 20 ° C (N / mm ² ) 112 123 > 85

¹ GMM is the theoretical maximum specific gravity (at zero porosity) of a bituminous conglomerate, measured in accordance with the AASHTO T 209 standard.

2GMB is the density of the conglomerate with voids (volumetric specific gravity) measured in accordance with the AASHTO T 166 standard.

³ ITS stands for tensile strength according to UNI EN 12697-23 at 25 ° C.

⁴ CTI indicates the coefficient of indirect tensile strength according to UNI EN 12697-23 at 25 ° C.

The percentage of residual voids after 10 cycles simulates the compaction of a bituminous conglomerate after the application of a paver; the percentage of residual voids after 120 cycles simulates the compaction of the bituminous conglomerate after rolling (i.e. after the paved road is open to traffic), and the percentage of voids after 200 cycles simulates the compaction of the bituminous conglomerate at the end of the asphalt pavement life (10-15 years) ).

According to the data given in table. 3, the wear layer made of conglomerate SMA1 containing the deicing composition according to Example 1 had GMM and GMB values completely comparable to those for conglomerate SMA2 without deicing composition, as well as excellent tensile strength and indirect tensile strength coefficient at stretching.

This means that the addition of the deicing composition of the present invention to a bituminous pavement conglomerate provides excellent protection against ice formation on the surface without significantly altering the physical and mechanical properties of the pavement obtained using the composition.

Example 9.

Conducted a comparative test of the composition in accordance with the present invention and the composition according to example 5, not containing dimethicone and corresponding to the known product Winterpav.

For testing, samples of bituminous conglomerate were made in accordance with the SMA curve, as shown in table. 5.

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Table 5

Bituminous conglomerate SMA1 containing the composition according to Example 1 Bituminous conglomerate SMA5 containing composition according to Example 5 Materials Bulk parts Bulk parts Inert materials 6/12 ten ten Inert materials 3/8 60 60 Sand 0-4 twenty twenty Filler (CaCO3) ten ten Plastomers and microfibers 0.6 0.6 Bitumen 50/70 6.5 6.5 Composition according to Example 1 4 0 Composition according to Example 5 0 4 Total 111.1 107.1

Samples were prepared by depositing about 1.2 kg of bitumen conglomerate in a cylindrical container, which was maintained at 150 ° C for at least 2 hours, and pressing it in a rotary press to form a corresponding cylindrical sample 100 mm in diameter and about 65 mm in height. For each sample, physical and mechanical measurements were carried out, indicated in table. 6.

Table 6

Conglomerate SMA1 Conglomerate SMA5 Specifications Residual voids (%) after 10 cycles 12.3 12.4 9-13 Residual voids (%) after 120 cycles 4.5 2.0 2-5 Residual voids (%) after 200 cycles 3.1 1, o > 1 GMM ¹ after 200 cycles (maximum specific gravity) (kg / m ³ ) 2399 2420 GMB ² after 200 cycles (bulk density) (kg / m ¹ ) 2301 2424 ITS ⁵ after 200 cycles 20'C (N / mm ² ) 1.28 1.60 1.0-1.80 CTI ⁴ after 200 cycles 20 ° C (N / mm ² ) 108 134 > 85

¹ GMM is the theoretical maximum specific gravity (at zero porosity) of a bituminous conglomerate, measured in accordance with the AASHTO T 209 standard.

2GMB is the density of the conglomerate with voids (volumetric specific gravity) measured in accordance with the AASHTO T 166 standard.

³ ITS stands for tensile strength according to UNI EN 12697-23 at 25 ° C.

⁴ CTI indicates the coefficient of indirect tensile strength according to UNI EN 12697-23 at 25 ° C.

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According to the data given in table. 6, the wear layer made from the conglomerate SMA1 containing the deicing composition according to Example 1 had GMM and GMB values completely comparable to those of the conglomerate SMA5 containing the deicing composition according to Example 5, as well as excellent tensile strength and indirect limit coefficient. tensile strength.

This means that the presence of polysiloxane in the deicing composition according to the present invention solved the above problem of overcoming the disadvantages inherent in the Winterpav product (the risk of inhalation of very fine particles contained in the powder and the caking phenomenon associated with hygroscopicity), while providing an equal deicing effect and does not impair the physical and mechanical properties of the road surface made of bituminous conglomerate containing the specified composition.

Example 10.

During storage of a batch of product with a composition according to example 1, the characteristics during storage in a warehouse at room temperature were monitored 1500 kg of the product, packed in two polyethylene big bags (FIBC), placed one on top of the other and placed on four bags of low-melting LDPE, each of which , in turn, contained 25 kg of the same composition. Two months later, the condition of the product was checked in two big bags, there was no caking, and in just 30 seconds the contents of the bags were emptied by gravity without noticeable formation of fine dust. No caking was found in four bags of fusible material.

Claims (20)

CLAIM 1. An anti-icing composition suitable for inclusion in bituminous conglomerates for paving, containing an alkali metal chloride, an alkaline earth metal carbonate, an alkali or alkaline earth metal formate and a polysiloxane, the content of said polysiloxane being from 0.5 to 2.0 wt% based on the total weight of the composition. 2. The deicing composition of claim 1, further comprising an alkaline earth metal chloride. 3. The deicing composition of claim 2, comprising an alkali chloride and an alkaline earth chloride, wherein said alkali metal chloride is sodium chloride and said alkaline earth chloride is calcium chloride. 4. The anti-icing composition of claim 3, wherein the alkaline earth metal carbonate is calcium carbonate. 5. The deicing composition of claim 4, wherein the formate is an alkali metal formate. 6. The deicing composition of claim 5, wherein said alkali metal formate is sodium formate. 7. An anti-icing composition according to claim 5, consisting of the following components, in weight percent based on the total weight of the composition: sodium chloride - 60-84, sodium formate - 5-15, calcium chloride - 5-15, calcium carbonate - 2-8, polysiloxane - 0.5-2.0. 8. An anti-icing composition according to any one of claims 1 to 7, characterized in that said polysiloxane is polydimethylsiloxane (dimethicone). 9. An anti-icing composition according to claim 8, characterized in that the viscosity of said polydimethylsiloxane is from 300 to 400 mm ² / s. 10. An anti-icing composition according to claim 9, characterized in that the viscosity of said polydimethylsiloxane is from 325 to 375 mm ² / s. 11. An anti-icing bitumen composition containing from 20 to 70 wt.% Of an anti-icing composition according to any one of claims 1 to 9 and from 30 to 80 wt.% Of bitumen. 12. The bitumen composition according to claim 11, containing from 30 to 60 wt.% Of the specified anti-icing composition and from 40 to 70 wt.% Bitumen. 13. Bituminous conglomerate configured to provide an anti-icing road surface containing aggregates, bitumen, filler and from 2 to 6%, based on the weight of said aggregates, of an anti-icing composition according to any one of claims 1-9. 14. The bituminous conglomerate according to claim 1, wherein the content of the deicing composition is 3 to 5% by weight, based on the weight of said aggregates. 15. A bituminous conglomerate capable of providing an anti-icing pavement containing aggregates, a filler and from 3 to 10 wt.%, Based on the weight of said aggregates of an anti-icing bitumen composition according to claim 11 or 12. - 8 036244 16. A method for producing a bituminous conglomerate according to claim 13 or 14, comprising the step of adding, with stirring and at a temperature of 130 to 200 ° C, bitumen and an anti-icing composition according to any one of claims 1-9 to a mixture of aggregates and filler. 17. A method for producing a bituminous conglomerate according to claim 15, comprising the step of adding, with stirring and at a temperature of 130 to 200 ° C, an anti-icing bitumen composition according to any one of claims 11, 12 to a mixture of aggregates and filler. 18. A method of obtaining an anti-icing composition according to claim 1, comprising the steps of mixing said alkali metal chloride, said alkaline earth metal carbonate and said alkali or alkaline earth metal formate to obtain a mixture in the form of a homogeneous powder and add said polysiloxane dispersed in finely divided form , to the specified mixture in the form of a homogeneous powder. 19. The method of claim 18, wherein said mixing step further comprises adding an alkaline earth metal chloride. 20. A method according to claim 18 or 19, characterized in that said step of adding polysiloxane is carried out by spraying the polysiloxane with a spray device onto said mixture in the form of a homogeneous powder, while the powder is mixed in a mixer, preferably a screw mixer.